


Knock Knock, Let the Devil In

by ScytheMeister7



Category: Compilation of Final Fantasy VII
Genre: Cannibalism, Canon-Typical Violence, Experimentation, Host Cloud Strife, Kinda, M/M, Symbiote Sephiroth
Language: English
Status: In-Progress
Published: 2021-01-16
Updated: 2021-01-15
Packaged: 2021-03-13 21:40:17
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,777
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28785084
Author URL: https://archiveofourown.org/users/ScytheMeister7/pseuds/ScytheMeister7
Summary: As if Cloud Strife has not already lived the worst life ever, it seems the Planet has more in store for him.In the form of a symbiote named Sephiroth.(In which Cloud Strife becomes Sephiroth's host and is put on Shinra's radar.A Venom AU based on Corzev's art)
Relationships: Sephiroth/Cloud Strife
Comments: 4
Kudos: 70





	Knock Knock, Let the Devil In

**Author's Note:**

> So, I had part of this written on twitter for a while (follow me @scythemeister__ if you'd like....) after being inspired by Corzev's very lovely Venom AU, and because I'm dumb and was a senior in, neglected to ever update it after a while. BUT NOW, i've graduated and have all the time in the world. Thought I'd post it here so that I'd also be more likely to update on an actual schedule, but...haha, I wouldn't count on that 100%. I will try my best tho. What matters is that I hope y'all like this fic
> 
> The first chapter is just stuff I've already posted on twitter, but with some added bits, but I promise I have the next chapter already started, so hopefully it doesn't take me ten years to finish it. Please enjoy, and also PLEASE check out Corzev on twitter and tumblr and everywhere else, her FF7 art is....delightful

Sometimes, the Planet decides she wants to have fun. She decides that she’s feeling a little bored and hatches the great idea of inviting a few guests over into her home, without the knowledge of its fellow residents. These guests will show up and decide ‘hey, I kind of like it here. I want to stay’, and somehow, someone ends up possessed or whatever by one of the Planet’s guests and things turn to shit faster than the Planet can say ‘whoops’. 

What this all is in the end is just a long winded analogy to try and explain that Cloud Strife is now the host of an alien parasite.

“Ow!”

A voice reverberates in his head, a little huffy and entirely inhuman. 

“ _ Symbiote _ , Cloud Strife. I am  _ not _ a parasite.”

\--

Cloud can’t remember the details, not that he’s sure he wants to in the first place. All he  _ can _ remember is the before and after, with just a bit of the middle sprinkled in for some flavour. Trying to push too hard just gives him a killer headache, plus his new...roommate? does nothing more than nag him for causing them both unneeded stress. Cloud would say that  _ Sephiroth _ is the unneeded stress in his life, but the only thing that gets him is aching teeth marks in his neck. Plus, whatever arrangement they find themselves in now, Cloud’s thoughts are no longer just his own.  _ No _ , he now shares them with this nightmare of a creature, and-- 

“Goddammit, Sephiroth! Stop biting me!”

There’s the mixture of a purr and a growl that makes Cloud’s head feel like it’s being shaken around and in his growing nausea, the sound leaks out of his own mouth, despite the fact that human vocal cords have no right being able to make such a sound. 

”If you cease your childish name calling, perhaps we can come to an understanding.” Is the response he gets, and Cloud’s teeth rattle. He spins his head to look at the...other head attached to his body in a way that makes him a different kind of nauseous. 

It’s been what Cloud thinks has been only a few days since this whole thing started in the first place, and he’s most definitely not used to the separate presence that seems to be attached to him permanently. Sephiroth is a weird mix of a humanoid looking creature with a set of teeth that err on the edge of a little  _ too _ sharp, skin the colour of paper, and slitted eyes an unnerving green that have kept him up for the past two nights as they stare at him the entire time, unblinking. His hair, or what Cloud considers to be hair when it isn’t used as the weird webbing that keeps them binded together, is long and equally as pale as his skin. In a strange way, Sephiroth is  _ attractive _ . 

Not that Cloud is focusing on that little detail at the moment. Instead, his hand flies up to his neck where he feels yet another set of indents. Luckily, he’s not bleeding this time, and Sephiroth has a gross look of smugness on his face. 

“ _ I’m _ childish? I’m not the one biting you every five seconds!” Frustration bleeds into Cloud’s words, but he feels like he deserves to feel this way. Afterall, this was the most stressful situation he’d ever been in, and Cloud was an  _ orphan _ . He’d lived that sad childhood of wanting to belong and it was only now that he’d managed to make friends, at the ripe age of twenty-one, and now he’s on the verge of losing them because he has a goddamn PARA-

Cloud pauses his thoughts.  _ Symbiote _ . He has a damn  _ symbiote _ bonded to him. 

Sephiroth rests his head on top of Cloud’s, something he seems to like doing, and hums. ”It is truly an unfortunate situation, I agree.” Cloud rolls his eyes and glances up at Sephiroth who in turn peers down at him, a smile edging on his lips. The nausea is replaced by a shiver despite his apartment being hot enough for him to nearly sweat through his hoodie. 

“It’s more than just ‘unfortunate’. I don’t even know what to do now. I can’t live like this. I can’t tell my friends. You’re stuck to me and I have  _ no idea _ how to get you  _ off _ and better yet, I don’t know what the fuck you even  _ are _ or why I was chosen in the fucking first place. I mean, one second I’m minding my own damn business on the street, and the next, I’m in a lab with a man standing over me with the greasiest hair I’ve ever fucking seen, and everything-”

Cloud is effectively quieted by what resembles a hand wrapping itself around his mouth. The texture is weird and he feels grossed out by it, but it’s gone almost as soon as it appeared. 

”You use vulgar words more often when you’re upset.” Sephiroth comments, and Cloud can’t do anything but just throw his hands up and groan, letting himself drop onto his couch with his face in his hands. He can feel Sephiroth…wrap himself around his body, in a way that’s a vague semblance of a hug, and despite his best efforts to resist, he’s tired, and maybe a bit touch starved. Cloud leans into the contact, as much as he can given their circumstances, and Sephiroth gives off a less body shattering purr, similar to that of one of Wedge’s cats. It’s comforting, and Cloud guesses that’s what Sephiroth was going for, though he has no idea why this alien symbiote would even care about his comfort in the first place. 

Sephiroth smiles and Cloud can feel it against his neck. 

“It’s because you’re mine now, Cloud.”

And because Cloud’s life is far from simple, that’s when someone decides to burst through his apartment door with a gun pointed at him. Several someones, actually. 

The redhead in front smiles around the stick of a lollipop. 

“Yo, are you Cloud Strife? I think you might’ve accidentally taken something that doesn’t belong to you.” 

\-- 

The details are fuzzy, but it doesn’t mean that Cloud remembers absolutely nothing. His arms still ache with the pain of being stabbed with needles and the sensation of his blood being on fire is something that’s unfortunately a bit difficult to scrub from his memory. He feels itchy, like his skin isn’t his own. Violated in a way that he’ll never be able to get rid of or forget. Sick. 

He sees flashes of green in his spotted memories, septic and poisonous, and his throat burns, like he’s been screaming for days with no end. Everything hurts, even if he’s no longer there, and a constant hum in the back of his mind, a voice whispering that  _ everything is fine, Cloud. Just let me in. _ only makes things worse. 

Cloud feels like he’s losing his mind. Everything is muddled with just the overwhelming sensation of  _ WRONG _ , and he can’t do anything to get rid of it, so he just curls in, hands to his ears in an attempt to block out the sounds, but they’re coming from inside him, so they do nothing. 

\--

Things move faster than Cloud can process. One second, he’s still seated on his couch, looking up at four people dressed in suits all pointing weapons at him, and the next, he can’t see anything before his vision flickers back into focus, only it’s so much different. Sephiroth’s deep rumbling voice vibrates through his entire body, something he thinks is meant to be comforting, but it doesn’t work as well as their half-hug that had been so rudely interrupted. 

Within what could only have been seconds, Cloud realizes what happened. Sephiroth had...taken over his body. Not like a puppet, but when he glances down, it’s like his body is covered in a second skin, the same pale white as Sephiroth. It feels like a vacuum seal over him and for a second, Cloud feels like he can’t breathe. 

“Calm down, Cloud. I’ll protect you.” Sephiroth says, but Cloud isn’t so sure he can follow those directions because those words come out of his own mouth and it is  _ not _ him saying them. 

There’s no time to actually try and process anything because a bullet whizzes by, and Cloud can almost see it go by in slow motion. His sight is much too clear and enhanced. This isn’t him. He isn’t doing this. It’s  _ Sephiroth _ . Pale, claw-tipped hands reach out in front of Cloud and grab the nearest of his sudden visitors, a man with dark hair and a fearful expression on his face. 

What happens next is something Cloud is glad he isn’t able to witness from an outside perspective, because experiencing it in first person is already nightmare fuel enough. It’s like his jaw unhinges, like a snake, wider than any human should possibly be able to open their mouth, and Cloud can taste human flesh on his too-long tongue, feel it get stuck between his teeth that jut out more than what would be comfortable, razor-sharp and dangerous. 

One second, there was a fully grown human man in front of him, and in the next, there was nothing more than a headless body. 

Cloud wants to pass out but something is preventing him. 

“Shit! What the  _ fuck _ Tseng?! You never said this fucker could bite off whole ass fuckin heads!” Cloud catches sight of the redhead as he drops his weapon, what looks like a nightstick with a taser on the end. Another man, who Cloud guesses to be Tseng even in his uneasy stupor of cold-blooded shock, grits his teeth and raises his weapon to Cloud again, but the third man grabs his wrist and drags him away. 

“It’s not worth it right now, we have to leave.”

Cloud feels like the villain. These people had broken into  _ his _ apartment, had threatened  _ him _ , but here he was, breathing heavy with the taste of blood still in his mouth, staining his chin down to his chest, a dead body on the ground. Cloud can feel Sephiroth tug at what’s essentially their shared body now, but Cloud still has more control, even in this state, and stands there frozen, watching as these men run away and escape from him. From the monster. He thinks he’d laugh if he was capable of producing any sort of sound right now. 

Cloud tries to process everything now that he’s no longer in imminent danger, and the conclusion he comes to is nowhere near comforting. 

Sephiroth is more than just a disembodied head that’s attached to him. No, whatever, Sephiroth is, whatever ‘symbiote’ means, it includes more than just that. Sephiroth can control him, take him over, use his body for his own purposes, and that scares Cloud more than the fact that he is now an accessory to murder. It meant that this won’t be the end. Wherever Sephiroth came from, had escaped from, those people will be looking for him, and they know Cloud will be dragged along. 

“Let me kill them, Cloud.” Sephiroth’s voice hisses, and he sounds  _ angry _ . There’s another tug, his feet itching to move forward, but Cloud manages to hold back. He feels hot and sweaty, and suddenly, he’s disoriented, his vision a mix of his normal human vision and the enhanced version that comes with being merged with Sephiroth. He catches sight of himself in a piece of mirror that must have broken from the first gunshot, and Cloud confirms it to himself. He’s a monster. 

The sight of half of his face poking out from the rest of what looks like a long-haired white beast is almost overwhelming. 

“Cloud…” Sephiroth says, and Cloud watches his own lips move. 

“Get off of me.” He replies. Even with only half a face, Cloud can see Sephiroth’s brow furrow. He looks like he’s going to argue, but Cloud doesn’t let him. “Get….GET  _ OFF _ OF ME!” 

It’s almost like he’s being skinned, as he watches in that tiny broken piece of mirror Sephiroth recede back into him, white skin making way for the clothing Cloud had been wearing before this whole thing happened, and his face is his own again, teeth human again, tongue a normal length. There’s still the taste of human in his mouth, but he can’t focus on that right now.

When he whips his head around, Sephiroth’s own face is nowhere to be seen, but Cloud knows he’s still there. Can feel him in his chest. It’s like he’s hiding, or sulking. 

“I’m not leaving, Cloud. But I will give you space.” Sephiroth’s voice is like it normally is again, echoing in his head, but Cloud doesn’t pay it any attention. He has to leave, get out of here before cops show up and see a _ headless body _ in front of him. 

Cloud employs a skill he’s good at and compartmentalizes. Pushes back the panic in his thoughts and grabs his wallet, keys, and phone. He makes his way down the stairs of his apartment, not willing to waste time waiting for the elevator. He enters the parking garage, spots Fenrir, and hops on without hesitation, revving the bike’s engine and leaving as fast as he can. He’ll think about what he’s going to do next later. Right now, he just needs to ride. 

\--

The first night is the most difficult. He can’t sleep, and it’s still unusual trying to settle into a body that looks like his own but also feels so foreign at the same time. Cloud learns his name. The voice in his head introduces itself. 

_ Sephiroth _ .

An unusual name for an unusual creature. Cloud doesn’t know what this thing is in the slightest, not even when it continuously claims to be something called a symbiote, but Cloud has  _ no idea  _ what the  _ fuck _ that is, and any attempt to look into it results in absolutely nothing. Instead, he’s stuck with this thing that keeps biting him like it’s a rabid dog, and the fact that it can even do that throws Cloud off so much he contemplates knocking himself out just to see if he wakes up sane again. 

Why him? 

Cloud can’t help but ask himself that as he looks into the mirror and is greeted by the sight of sharp teeth and thin lips curved up in a smile. 

\--

Driving without thinking leads to Cloud pulling up in front of Tifa’s apartment about an hour later. He hadn’t really planned on coming here, but with an empty head and fear racing through his veins, it appears as though his instincts had taken over. Sephiroth, who’d been quiet during the entire ride, makes a disgruntled noise in the back of Cloud’s head, but he ignores it as he parks Fenrir and tucks his helmet under his arm before heading to the building entrance. 

Pressing on the call button next to Tifa’s apartment number, it doesn’t take long for her voice to emanate from the dingy speaker. 

“Cloud? What are you doing here? You normally call first.” She sounds as motherly as ever, and it’s something like a comfort to Cloud. 

“Yeah...I… Just, let me up, Tifa? I’ll explain face to face.” 

A few minutes later and Cloud is pacing in Tifa’s apartment with a cup of tea between his hands that Tifa had handed him as soon as she’d opened her door. 

“So…” She says softly from her position on the couch. “Are you going to explain?” 

Cloud pauses mid pace and turns to face her. With the way his mind had been blank the entire way here, Cloud had no actual idea what he was going to say now. He hadn’t even planned on coming here in the first place, but there was no way to go back. Cloud doesn’t want to drag Tifa into this, because Cloud doesn’t even know what  _ this _ is, but she’s his oldest friend and maybe the person he trusts the most in the world.

“I…” He pauses, thinks over his words again, sighs, and then continues. “I have a parasite in me.” 

_ That _ certainly gets the reaction he wants, and almost immediately. He knows trying to explain to Tifa what a symbiote is would go nowhere, and Sephiroth doesn’t feel like he’s in a ‘show and tell’ mood at the moment with how much Cloud can feel him fuming in the back of his head for some reason. So, he does the one thing he knows will get the symbiote to act out, and deals with an addition to the collection of teeth marks on his neck. It barely hurts anymore, so Cloud’s flinch is more from annoyance than pain. 

Tifa gasps, standing up immediately, and Sephiroth…Sephiroth  _ hisses _ . 

“I am  _ not _ a parasite, Cloud. It would do you well not to use that word simply just to provoke a response.” Sephiroth’s voice is an angry growl and Cloud rubs at his neck, feeling somewhat apologetic, but not enough for him to voice it out loud. 

“You were quiet the whole way here, Sephiroth, I had to get you out somehow.” 

“Why? So you can show me off to this human woman who might give us away to authorities? You can’t trust anyone, Strife. Anyone but  _ me _ .” 

There’s a wave of jealousy that floods Cloud’s body for just a moment before it’s gone, and it’s only then that he realizes what’s going on, why Sephiroth is acting like a feral cat, possessive over their belongings. 

“Tifa would never do that, Sephiroth! If this whole emotional and physical connection shit is anything real, then you can  _ see _ my memories. Tifa is one person we can  _ trust _ .” 

Tifa makes a sound at that, bringing Cloud’s attention back to her as he realizes she’d been subject to watching her best friend and some…. _ thing _ argue right in front of her. 

“I...honestly don’t know what’s going on, and I expect a full explanation,” she turns a brief glare to Cloud as she says that, “but I’d never call the cops on you, or whatever other authorities.” Her eyes are wide as she takes in Sephiroth’s form, moving from his bright eyes to his sharp teeth, his mouth twisted into a snarl, before continuing up to his hair and then finally landing on the possessive hold he has on Cloud’s shoulders. He looks... _ incredibly _ dangerous, but there’s no tension in Cloud’s body, or at least, not related to the fact that there’s this scary white demon thing digging sharp claws into his skin right now. He merely looks bothered. 

Cloud slaps a hand over Sephiroth’s and frowns over his shoulder at him. “Stop that,” he says, “and behave. Just...help me explain to Tifa, alright? I don’t know who those people who came after me... _ us _ are, but I figure they’re not going to stop. We can’t go back to my apartment which means we need somewhere else to lay low until we figure  _ something _ out, so for now...just work with me, okay? And by that, I mean be  _ nice _ .” 

He raises the mug of tea to his mouth and grimaces at the now lukewarm drink, but he forces himself to swallow it down before setting the mug on the coffee table. 

“I’m...not really sure how to start,” he admits, wringing his hands slightly, “but basically...well. Sephiroth is an alien. I think. And I was kidnapped about...two days ago? I can’t remember the details, they’re all fuzzy, and honestly, it just gives me a headache, but some guy in a lab...he  _ put _ Sephiroth in me, as a test to see if we could bond together or whatever, but it wasn’t supposed to be a permanent thing for some reason, but Sephiroth got... _ attached _ to me. Didn’t want to leave, and so somehow, we managed to break out of the lab or whatever. I went back home and for the past two days, it’s been fine, if not confusing, and then today, some guys showed up saying I ‘stole’ Sephiroth and attacked us. Sephiroth managed to...apprehend them, and we got away, and then I drove us here. And now I need help finding a way out of all of this.” 

Cloud isn’t used to speaking this much all at once and he almost wishes he had more tea, but he just stands there in Tifa’s living room as she watches him with wide eyes. Sephiroth moves beside him, hands releasing their grip on his shoulders before he feels them sliding to hug around his neck, Sephiroth’s face cuddling up next to his cheek. 

“You’re the perfect host, Cloud. It’s like you were made specifically for me. There’s no way I’m going to give you up, I refuse.” Green eyes flicker up to meet Tifa’s. “I  _ am _ an alien, as Cloud put so eloquently. How I arrived at your pitiful planet, it is unknown to me. I’ve been asleep for a very long time. However, it would seem your human scientists found me to be an interesting specimen, and supposedly, their strongest, which would explain their reasoning for wanting to separate me from Cloud, and why they’re adamant about taking me back. However, these things are not going to happen. Cloud is mine now, and I will protect him.” 

As if that’s the end of his own explanation, Sephiroth tucks his face further into Cloud’s neck and purrs softly, the sensation ticklish, but not enough for Cloud to shove him away. 

“That’s…” Tifa pauses, trying to find the words in her mind to properly facilitate her thoughts. Cloud doesn’t blame her, seeing as how he has yet to understand everything himself. 

Tifa sighs. “I understand.” 

At that, Cloud raises an eyebrow.

“You do?”

Tifa laughs. “Not at all, but I know I’m not going to, even if I try. Whatever is happening, I understand enough to know we have a lot of work to do, and it’s going to require more than just my help.”

Cloud groans, because he knows where this is leading and he’s not ready to face everyone right now, and especially not like this. Sephiroth makes an inquiring sound against his skin, but Cloud just reaches a hand up to pat at his head.

“Please, just...tell Barret first, then? It’ll give him the most time to process everything, and maybe he won’t kill me.”

Tifa grins at that. “Don’t worry! I’m sure Sephiroth here wouldn’t let that happen anyway.”

Sephiroth raises his face from Cloud’s neck and instead rests his chin on his shoulder. “Hmm, maybe she’s alright…”


End file.
